Abstract

Rubella virus (RV) associated granulomatous dermatitis is a rare entity seen in patients with primary immunodeficiencies in which RV, commonly from vaccine exposure, persists and triggers a chronic granulomatous response. This entity has been discussed in the microbiology and immunology literature but is an emerging, infrequently reported diagnosis in the dermatology/pathology literature. We present a case of RV associated granulomatous dermatitis in a 57-year-old woman with common variable immunodeficiency and inflammatory arthritis. She presented with a 4-year history of painful, erythematous papules and plaques that were initially limited to her hands and progressed to involve her face, chest, back, and upper and lower extremities. The rash showed some improvement with infliximab, and cyclosporine was also started. She underwent 8 different skin biopsies since 2016 and 5 of them, including our case, showed granulomatous dermatitis while the others showed interface dermatitis. Our case, a biopsy of her right arm, showed ill-defined, tuberculoid-type granulomas with admixed lymphocytes and occasional multi-nucleated giant cells involving the superficial to deep dermis. Gram, periodic acid-schiff with diastase, acid fast bacteria, and fite special stains were negative for pathogenic organisms, and no polarizable foreign material was identified. Per the dermatologist’s request, the biopsy specimen was sent to an outside institution for RV immunofluorescence (IF) studies. IF showed RV capsid protein signaling localized to M2 macrophages. Based on this finding, cyclosporine was discontinued, and nitazoxanide, a broad anti-viral medication, was prescribed. Dermatopathologists should be aware of RV-associated granulomatous dermatitis and consider it in the context of chronic, refractory granulomas in primary immunodeficient patients as making the diagnosis may change management and prevent misdiagnosis of other granulomatous lesions.

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